To validate or not to validate? - that is the question!

ok this may end up more of a discussion rather than a issue with anything specific… but where do you draw the line on validation…

the site im thinking of is currently work in progress… www.onsetcold.co/index1.htm

the code is well written clean css on the main page - not the iframe… the iframe content does contain transitional html and does include a few tables etc…

now i know im gonna be handing over a proportion of the site to the band members and i know within weeks there will be <font> tags appearing etc… in the iframe…

so… why validate at all?

becuase as a purist of the web i want to design to that standard… surely a common thing on this forum… so thinking do i just validate the main page and leave the iframe… is there a way i can validate the main page and the iframes… or is it worth just forgetting it all together??

help!?